What Try means is that the Acrobat scripting environment is sandboxed for security, and so the model has very limited access to the local file system. There simply is no functionality for what you want to do.

So, your best option, since your task is all in the file system, is to use an easily accessible scripting/programming language for your system. Something like Batch Scripting if you are on Windows, or AppleScript if you are on a Mac.

If you are a VB programmer, then that is the best way to do it on Windows

Also lookup "Windows Scripting" on Google.

Well Actually, there is a way to do something like this in Acrobat. You can create an "Action" that will open all the files in a folder and save them to a different folder with new names. But not as clean as the previously discussed solutions.